The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.Sánchez et al., 2006
At its base, this formation conformably overlies the Plottier Formation of the older Río Neuquén Subgroup, and it is in turn overlain by the Anacleto Formation, the youngest and uppermost formation of the Neuquén Group.Fossa Mancini et al., 1938
The Bajo de la Carpa Formation can reach in thickness in some locations, and consists mainly of sandstones of various colors, all of fluvial origin, with thin layers of mudstone and siltstone in between. Geological features such as geodes, chemical nodules, impressions of raindrops, and paleosols (fossil soils) are commonly found in this formation as well.
Fossil content Small nests with eggs inside, found in this formation, probably belonged to the bird Neuquenornis.Leanza et al., 2004 Fossil wasp nests have also been found in these rocks.
Fish Fish reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesRinconodusR. salvadoriA ceratodontid lungfish
Reptiles
Crocodylomorphs Crocodylomorphs reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesBarrosasuchusB. neuquenianusCoria et al., 2019 Sierra Barrosa Upper A skull articulated with the remaining skeleton, which consisted of both forelimbs, most of the vertebral column up to the sacra, one hindlimb, and semi-articulate osteoderms that obscured parts of the fossil A peirosaurid notosuchianComahuesuchusC. brachybuccalis Universidad Nacional del Comahue Upper A holotype specimen A comahuesuchid notosuchian CynodontosuchusC. rothi A baurusuchid notosuchianGasparinisuchusMartinelli et al., 2012 G. peirosauroides Loma de la Lata Upper A partial skull, lower jaws, and various associated postcranial remains A peirosaurid notosuchian KinesuchusK. overoiFilippi et al., 2018a Cerro Overo Upper A partial mandible An itasuchid notosuchian Lomasuchus L. palpebrosus A peirosaurid notosuchian NeuquensuchusN. universitasLio et al., 2018 Universidad Nacional del Comahue Upper Paratype specimens consist of a partially articulated partial postcranial skeleton and left leg bone. A crocodyliform of uncertain placementNotosuchus N. lepidus A notosuchid notosuchian N. terrestrisPeirosaurusP. torminni A fragmentary skull and a partial postcranial skeleton. A peirosaurid notosuchian Wargosuchus W. australis Northern region of the Neuquén city A partial right premaxilla and maxilla, and partial skull roof. A pissarrachampsine baurusuchis
Ornithischians Ornithischians reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesAnkylosauriaIndetermidateIguanodontiaIndetermidate Cerro Overo A femur An early juvenile iguanodontian of uncertain affinities, possibly a Rhabdodontomorph. MahuidacursorCruzado Caballero et al., 2019M. lipanglef Cerro Overo Upper A set of postcrania An elasmarian
Sauropods Sauropods reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesBonitasauraB. salgadoi A partial sub-adult skeleton with a lower jaw, a partial vertebrae series, and limb bones. A titanosaur InawentuI. oslatus Rincón de los Sauces A partially articulated skeleton, including a nearly complete skull, Several vertebrae from the atlas to the end of the sacrum, and both ilia A titanosaur Overosaurus O. paradasorum Upper A fully articulated vertebral series consists of rib bones, dorsals, and ilium A titanosaurRinconsaurusR. caudamirus Rincón de los Sauces Lower The fossil remains included vertebrae, limb bones, scapula, hip bones (pubis, ilium, and ischium) and several ribs. A titanosaur TraukutitanT. eocaudata Sitio Trauku Lower A partial semi-articulated skeleton including both thigh bones and thirteen vertebrae from the anterior and middle tail A titanosaur YeneenY. houssayi La Invernada Lower A disarticulated skeleton including vertebrae from all major regions, the ilia, and ribs, in addition to an isolated ilium of a second individual and a third undescribed specimen A titanosaur
Theropods Theropods reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesAchillesaurus A. manazzonei Paso Córdova Upper A partial skeleton consists of a sacral vertebra, four tail vertebrae, part of the left thighbone, shin, and foot, and the left ilium. An alvarezsauridAlvarezsaurusA. calvoi Boca del Sapo, Upper A set of postcrania An alvarezsauridDiuqinD. lechiguanae"the isthmus between the southeast coast of Lago Barreales and the northwest coast of Lago Mari Menuco" UpperA fragmentary but associated partial skeletonAn unenlagiine LlukalkanFilippi et al., 2018bL. aliocranianus La Invernada site. Upper A partial skull. An abelisauridNeuquenornisN. volans Boca del Sapo Upper A skull and a partial postcranial remains. An enantiornitheanPatagopteryxP. deferrariisi Boca del Sapo Upper A partial, incomplete skeleton consisting of 18 vertebrae, synsacrum, and much of the pectoral and pelvic girdles, wings, and hindlimbs. A flightless euornitheanTratayeniaPorfiri et al., 2018T. rosalesi Traytenia locality Upper A well-preserved partial skeleton A megaraptoran VelocisaurusV. unicus Universidad Nacional del Comahue Upper A set of limb elements. A noasaurid ViavenatorV. exxoni La Invernada Upper A partial skeleton An abelisaurid
Other reptiles Other reptiles reported from the Bajo de la Carpa Formation Genus Species Location Stratigraphic position Material Notes ImagesLomalatachelysF. d.e. Lapparent de Broin and M. S. de la Fuente. 2001. Oldest world Chelidae (Chelonii, Pleurodira), from the Cretaceous of Patagonia, Argentina. C. R. Acad. Sci. Paris, Sciences de la Terre et des planètes 333:463-470.L. neuquinaA chelid turtleDinilysiaD. patagonicaA snakePaleochelcoP. occultatoA lizardPodocnemidoideaIndeterminate
See also List of fossil sites List of dinosaur bearing rock formations Mata Amarilla Formation, contemporaneous formation of the Austral Basin
References
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Further reading